docs: def all_tokens(self, delimiter=' ', label_list_ids=None):
          """
          Return a list of all tokens occurring in one of the labels in the corpus.
  
          Args:
              delimiter (str): The delimiter used to split labels into tokens
                               (see :meth:`audiomate.annotations.Label.tokenized`).
              label_list_ids (list): If not None, only labels from label-lists with an idx contained in this list
                                     are considered.
  
          Returns:
               :class:`set`: A set of distinct tokens.
          """
          tokens = set()
  
          for utterance in self.utterances.values():
              tokens = tokens.union(utterance.all_tokens(delimiter=delimiter, label_list_ids=label_list_ids))
  
          return tokens